1. Field of the Invention
The present invention relates to an image forming apparatus and an image forming method for forming an image on one side or both sides of a sheet.
2. Description of Related Art
According to the conventional image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 2001-125439, Japanese Patent Application Laid Open No. 11-157725 (1999) and the like, image data is generated by reading one side of an original, for example. The image forming apparatus then forms an image on one side of a sheet using the image data and discharges the sheet to a sheet receiving tray with said side down (face-down method).
FIG. 1 is a flowchart showing procedures of a user for forming an image with a conventional image forming apparatus 3 (see FIG. 3A). A sheet having the same attribute at both sides, on each of which sides image can be formed, is held in a sheet holding tray in the image forming apparatus 3. The image forming apparatus 3 forms an image on one side of the sheet when default image forming conditions (printing conditions) is used.
The user sets an original in an original retainer or an automatic original conveying unit provided in the image forming apparatus 3 (step S1). The user then determines whether an image is to be formed on both sides of the sheet (i.e., double-side printing is to be performed) or not (step S2). If the double-side printing is to be performed (YES at step S2), the user operates a double-side print key at an operation display provided in the image forming apparatus 3 (step S3). If an image is to be formed on one side of the sheet (i.e., single-side printing is to be performed) (NO at step S2), the user does not operate the double-side print key (the default printing conditions are used).
The user then determines whether a sheet having different attributes at respective sides (for example, a sheet having a letterhead on one side, an OHP sheet having one side on which printing is possible and the other side on which printing is not possible or the like, which is referred to as a special sheet hereinafter) is to be used or not (step S4). If the special sheet is to be used (YES at step S4), the user sets the special sheet in the sheet holding tray (step S5). At this time, the user sets the special sheet in the sheet holding tray with the front side up for performing single-side printing, or sets the special sheet in the sheet holding tray with the front side down for performing double-side printing.
If the special sheet is not to be used (NO at step S4), a sheet in a sheet holding tray is used.
Last of all, the user sets the printing conditions such as magnification or color strength of an image to be formed, the number of sheets or the like (step S6) and operates a printing key (step S7).
FIG. 2 is a flowchart showing processing procedures of image formation and sheet conveyance of the image forming apparatus 3.
The image forming apparatus 3 determines whether the printing key has been operated or not (step S11). If the printing key has not been operated (NO at step S11), the image forming apparatus 3 waits until the printing key is operated. If the printing key has been operated (YES at step S11), the image forming apparatus 3 starts to read the original set in the original retainer or the automatic original conveying unit (step S12) and generates image data from the read image.
The image forming apparatus 3 then determines whether the sheet is to be reversed or not by determining whether the double-side print key had been operated or not before the printing key was operated (step S13). More specifically, if the double-side print key had been operated, the image forming apparatus 3 forms the image on one side of the sheet and then reverses the sheet to form an image on the other side. If the double-side print key had not been operated, the image forming apparatus 3 forms the image on one side of the sheet and discharges the sheet without reversing the sheet.
If the double-side print key had not been operated (NO at step S13), the image forming apparatus 3 performs single-side printing process. In the first place, the image forming apparatus 3 supplies a sheet from a sheet holding tray to a printer provided in the image forming apparatus 3 (step S14), forms an image on one side of the sheet using the image data (step S15) and discharges the sheet to the sheet receiving tray (step S16).
Last of all, the image forming apparatus 3 determines whether the next original is to be read or not (for example, whether there is an unread original in the automatic original conveying unit or not) (step S17). If the original is to be read (YES at step S17), the operation returns to step S12. If no original is to be read (NO at step S17), the operation returns to step S11.
If the double-side print key had been operated (YES at step S13), the image forming apparatus 3 performs the double-printing process. In the first place, the image forming apparatus 3 stores the image data in an image memory provided in the image forming apparatus 3 as first image data (step S18), starts to read the next original (step S19) and generates the second image data from the read image.
The image forming apparatus 3 then supplies a sheet from the sheet holding tray to the printer (step S20) and forms the second image on one side of the sheet using the second image data (step S21).
The image forming apparatus 3 then reverses the sheet (step S22), forms the first image on the other side of the sheet using the first image data read from the image memory (step S23) and discharges the sheet to the sheet receiving tray (step S24). The operation then returns to step S17.
FIGS. 3A through 4 are explanatory drawings showing procedures of image formation and sheet conveyance of the image forming apparatus 3 with which the single-side printing is performed.
The image forming apparatus 3 comprises a sheet holding tray 210 for holding one or a plurality of sheets P, and a feeder 211 for supplying one sheet after another held in the sheet holding tray 210 to a printer 20. Each sheet P is held in the sheet holding tray 210 with one side PA (front side in case of the special sheet) of the sheet P up and the other side PB down.
The sheet P which has been supplied to the printer 20 from the sheet holding tray 210 by the feeder 211 is sequentially conveyed to the position between the photoconductor 200 and the imprinter 203 in the direction shown by an outline arrow such that the one side PA is in contact with the photoconductor 200. When the sheet P is disposed between the photoconductor 200 and the imprinter 203, an image is formed on the one side PA (referring to FIG. 3A).
The sheet P passes through a fixer 23 and the image is fixed onto the one side PA of the sheet P. The sheet P is then conveyed in the direction shown by an outline arrow by the guide-in/guide-out roller 28 to the transit conveyance unit 18 (referring to FIG. 3B) and reaches the transit conveyance unit 18 with the one side PA down and the other side PB up (referring to FIG. 3C). The sheet P is then discharged to the sheet receiving tray 56 by the guide-out roller 53 (referring to FIG. 4).
In a case where a plurality of sheets P are discharged by the guide-out roller 53, the sheets P are sequentially stacked in the sheet receiving tray 56 with the one side PA, on which an image is formed, facing down.
FIGS. 5A through 7C are explanatory drawings showing procedures of image formation and sheet conveyance of the image forming apparatus 3 with which the double-side printing is performed. Each sheet P is held in the sheet holding tray 210 with one side PA (front side in case of special sheet) of the sheet P down and the other side PB up.
The sheet P which has been supplied to the printer 20 from the sheet holding tray 210 by the feeder 211 is sequentially conveyed to the position between the photoconductor 200 and the imprinter 203 in the direction shown by an outline arrow such that the other side PB is in contact with the photoconductor 200. When the sheet P is disposed between the photoconductor 200 and the imprinter 203, a second image is formed on the other side PB (referring to FIG. 5).
The sheet P passes through the fixer 23 and the second image is fixed onto the other side PB. The sheet P is then conveyed in the direction shown by an outline arrow, by the guide-in/guide-out roller 28 rotating in the forward direction, to the transit conveyance unit 18 (referring to FIG. 5B) and reaches the transit conveyance unit 18 with the other side PB down and the one side PA up (referring to FIG. 5C). The sheet P is then conveyed in the backward direction (shown by an outline arrow) by the guide-in/guide-out roller 28 rotating in the backward direction (referring to FIG. 6A), to the reversal and conveyance unit 11 (referring to FIG. 6B) and is sequentially conveyed from the reversal and conveyance unit 11 to the position between the photoconductor 200 and the imprinter 203 of the printer 20 such that the one side PA is in contact with the photoconductor 200. When the sheet P is disposed between the photoconductor 200 and the imprinter 203, a first image is formed on the one side PA (referring to FIG. 6C).
The sheet P passes through the fixer 23 and the first image is fixed onto the one side PA of the sheet P. The sheet P is then conveyed in the direction shown by an outline arrow, by the guide-in/guide-out roller 28 rotating in the forward direction, to the transit conveyance unit 18 (referring to FIG. 7A) and reaches the transit conveyance unit 18 with the one side PA down and the other side PB up (referring to FIG. 7B). The sheet P is then discharged to the sheet receiving tray 56 by the guide-out roller 53 (referring to FIG. 7C).
In a case there a plurality of sheets P are discharged by the guide-out roller 53, the sheets P are sequentially stacked in the sheet receiving tray 56 with the one side PA, on which the first image is formed, facing down.
As described above, the image forming apparatus 3 can discharge sheets on which the image is formed in order of the originals.
However, for forming an image on a special sheet using the image forming apparatus 3 employing the face-down method, there arises a problem that the image forming apparatus 3, in which the special sheet is held in the sheet holding tray 210 with the front side thereof up, forms an image on the front side of the sheet if single-side printing is performed but forms the image to be formed on the front side of the special sheet on the back side thereof if double-side printing is performed.
Thus, for forming the image on one side of the special sheet, it is necessary for the user to set the special sheet in the sheet holding tray 210 with the front side up while, for forming the image on both sides thereof, it is necessary to set the special sheet in the sheet holding tray 210 with the back side thereof up. Consequently, the procedures of the image formation become troublesome.
In addition, it is necessary to store the first image data for forming the first image (image on the front side) in the image memory until formation of the second image using the second image data (image on the back side) is finished. As a result, it is necessary to provide an image memory having large capacity capable of storing both of the first and second image data.
Furthermore, according to an image forming apparatus which does not store the first image data in the image memory in a case where the double-side printing is performed, the first image is formed on the sheet conveyed to image forming means when the front side of the original is read, the sheet is reversed and the second image is formed when the back side of the original is read. Therefore, the sheet is discharged in the sheet receiving tray with the back side down, so that the sheet can not be discharged in order of the originals. If the aforementioned image forming apparatus is used, it is necessary to read the originals from back side thereof in order to discharge the sheets in order of the originals. As a result, the procedures in forming the image become complicated.
The present invention has been made to solve the above problems and it is an object thereof to provide an image forming apparatus which can discharge the sheets in order of the originals without troublesome procedures of a user for forming an image.
It is another object of the present invention to provide an image forming apparatus which can discharge sheets in order of the originals without troublesome procedures of a user for forming an image in a case where an image is formed on a special sheet having different attributes at respective sides, and can improve efficiency in forming an image in a case where an image is formed on a sheet other than the special sheet.
It is a further object of the present invention to provide an image forming apparatus which can discharge sheets in order of the originals without troublesome procedures of a user for forming an image in a case where an image is formed on both sides of a sheet and can improve efficiency in forming an image in a case where an image is formed on one side of the sheet.
It is still another object of the present invention to provide an image forming apparatus which can discharge sheets in order of the originals without troublesome procedures of a user for forming an image in a case where an image is formed on one side of the sheet and can prevent deterioration of a sheet and occurrence of conveyance miss while the sheet is conveyed in a case where an image is formed on both side of the sheet.
It is still a further object of the present invention to provide an image forming apparatus which can improve efficiency of image formation and prevent deterioration of a sheet and occurrence of conveyance miss while the sheet is conveyed.
It is still a further object of the present invention to provide an image forming method which can reduce storage capacity of storage means (an image memory) which stores data of the image until the image is formed on the sheet.
It is still another object of the present invention to provide an image forming method which can prevent a jam of the image-formed sheet from occurring while an image is formed on both sides of a sheet.
It is still another object of the present invention to provide an image forming method which can prevent a jam of an image-formed sheet from occurring while an image is formed on one side of a sheet.
It is still a further object of the present invention to provide an image forming method which can discharge sheets in order of the originals in a case where a sheet, for which it is to be determined whether an image is to be formed or not on the sheet conveyed to image forming means, and a sheet, for which it is not to be determined whether an image is to be formed or not on the sheet conveyed to the image forming means, are sequentially processed.
An image forming apparatus according to the present invention comprises image forming means for forming an image on a sheet; conveying means for conveying the sheet to the image forming means; reversal means for reversing the sheet; and control means for determining whether the sheet is to be reversed or not and controlling the conveying means and the reversal means to reverse the sheet and convey it to the image forming means when it has been determined that the sheet is to be reversed. The control means includes means for determining whether an image is to be formed on the sheet conveyed to the image forming means or not; means for controlling the conveying means and the image forming means to convey the sheet to the image forming means and to form the image on the sheet when it has been determined that the image is to be formed; and means for controlling the conveying means to convey the sheet to the image forming means when it has been determined that the image is not to be formed.
The image forming apparatus discharges the sheet to a sheet receiving part (sheet receiving tray, for example) by a face-down method.
The controlling means determines whether an image is formed or not on the sheet conveyed to the image forming means. If it has been determined that the image is to be formed, the control means controls the conveying means and the image forming means to convey the sheet to the image forming means, form the image on the sheet and let the sheet pass through the image forming means. Alternatively, if it has been determined that the image is not to be formed, the control means controls the conveying means to convey the sheet to the image forming means and let the sheet pass through the image forming means. At this time, the control means prohibits the image forming means from forming an image (referred to as idle conveyance hereinafter).
For example, when a sheet is held in supply means for supplying the sheet (a sheet holding tray, for example) with one side thereof up, the sheet supplied from the sheet holding tray is conveyed to the image forming means with the one side facing toward the image forming means.
At the time of single-side printing, when the original was read, the control means controls the image forming means to form an image on the sheet conveyed to the image forming means and discharges the sheet to the sheet receiving tray. In this case, the sheet is discharged to the sheet receiving tray with the image-formed side down.
At the time of double-side printing, when the original was read, the control means determines whether an image is to be formed or not on a sheet (one side) conveyed to the image forming means. At this time, the control means determines to form the image and forms the image corresponding to the image of the front surface of the original on the sheet. The control means controls the reversal means to reverse the sheet and conveys the sheet to the image forming means. Then, when the back side of the original was read, the control means determines whether an image is to be formed or not on the sheet (the other side) conveyed to the image forming means. At this time, the control means determines to form the image and forms the image corresponding to the image of the back surface of the original on the sheet. The control means controls the reversal means to reverse the sheet and conveys the sheet to the image forming means. The control means then determines whether an image is to be formed or not on a sheet (one side on which the image has been already formed) conveyed to the image forming means. At this time, the control means determines not to form the image and performs the idle conveyance to discharge the sheet to the sheet receiving tray. In this case, the sheet is discharged to the sheet receiving tray with the one side, on which the image corresponding to the image on the front side of the original was formed, facing down.
The above-described image forming apparatus can discharge sheets (special sheets) in order of the originals read. In addition, the image forming apparatus can form the image in such a manner that the front surface of the original corresponds to the one side of the sheet (the front side of the special sheet). Therefore, even when the special sheet is set in the sheet holding tray, it is not necessary for the user to determine whether the front side of the special sheet is to face up or down. Thus, even when the special sheet is set in the sheet holding tray upside down, it is not necessary to reverse the sheet manually. In other words, user convenience can be improved.
The image forming apparatus according to the present invention may further comprise obtaining means for obtaining information on whether the sheet has a predetermined attribute or not. In this case, according to the presence or absence of the attribute, the control means determines whether an image is to be formed or not on the sheet conveyed to the image forming means.
The image forming apparatus comprises, as the obtaining means, a sheet attribute key corresponding to the predetermined attribute and a printing key which instructs the apparatus to start sheet conveyance and image formation processing, in an operation part thereof, for example. If the user operated the printing key after operating the sheet attribute key, the control means determines that information that the sheet has the attribute corresponding to the sheet attribute key was obtained. If the user operated the printing key without operating the sheet attribute key, the control means determines that the information that the sheet does not have the attribute corresponding to the sheet attribute key was obtained.
Furthermore, if there are a first attribute (attribute such as a special sheet, for example) of a sheet on which an image is not formed often and a second attribute (attribute such as a standard sheet other than the special sheet) of a sheet, other than the first attribute, on which an image is formed often, the control means may be structured to determine that the information that the sheet has the second attribute was obtained when the user operated the printing key without operating the sheet attribute key corresponding to the first attribute. At this time, since the user can omit the procedure of operating the sheet attribute key in a case where the image is formed on the sheet of the attribute for which the image is formed often, the user convenience can be improved.
As described above, if the control means has determined that the sheet has the predetermined attribute (or does not have the predetermined attribute), the control means determines whether an image is to be formed on the sheet conveyed to the image forming means or not. When the image is formed, the control means conveys the sheet to the image forming means and forms an image on the sheet while, when the image is not formed, the control means conveys the sheet to the image forming means but does not form an image. Therefore, sheets can be discharged in order of the originals without complicating the procedures of a user for forming the image.
According to the image forming apparatus of the present invention, the obtaining means may obtain information on whether the sheet has different attributes at respective sides or not. In this case, if the information that the sheet has different attributes at respective sides has been obtained, the control means determines whether an image is to be formed or not on the sheet conveyed to the image forming means.
According to this image forming apparatus, when a special sheet is held in the sheet holding tray with front side thereof up, for example, and the special sheet supplied from the sheet holding tray is conveyed to the image forming means with the front side facing toward the image forming means, the image forming apparatus forms an image on the special sheet (front side) conveyed to the image forming means and discharges the sheet to the sheet receiving tray when the original was read at the time of the single-side printing. In this case, the special sheet is discharged to the sheet receiving tray with the image-formed side down.
At the time of the double-side printing, when the original was read, the control means determines whether the image is to be formed or not on a special sheet (front side) conveyed to the image forming means. At this time, the control means determines to form the image and forms the image corresponding to the image of the front surface of the original on the special sheet. The control means reverses the special sheet and conveys the sheet to the image forming means. Then, when the back side of the original was read, the control means determines whether an image is to be formed or not on the special sheet (the back side) conveyed to the image forming means. At this time, the control means determines to form the image and forms the image corresponding to the image of the back surface of the original on the special sheet. The control means reverses the special sheet and conveys the sheet to the image forming means. The control means then determines whether an image is to be formed or not on a special sheet (front side on which the image has been already formed) conveyed to the image forming means. At this time, the control means determines not to form the image and performs the idle conveyance to discharge the special sheet to the sheet receiving tray. In this case, the special sheets are discharged to the sheet receiving tray with the front side, on which the image corresponding to the image on the front surface of the original is formed, facing down.
The above-described image forming apparatus can discharge the special sheets in order of the original read. In addition, the image forming apparatus can form the image in such a manner that the front surface of the original corresponds to the front side of the sheet.
Furthermore, since the above image forming apparatus does not determine whether the image is to be formed on the sheet or not nor perform the idle conveyance when an image is formed on the sheet other than the special sheet, conveying time of the sheet is decreased and the efficiency of the image formation can be improved.
The image forming apparatus according to the present invention may further comprises means for obtaining information on whether an image is to be formed on one side or both sides of the sheet. In this case, if the information that the image is to be formed on both sides of the sheet was obtained, the control means determines whether the image is to be formed or not on the sheet conveyed to the image forming means.
Since this image forming apparatus does not determine whether the image is to be formed or not on the sheet nor perform the idle conveyance when the single-side printing is performed, conveying time of the sheet is decreased and the efficiency of the image formation can be improved.
The image forming apparatus according to the present invention may further comprise means for obtaining information on whether an image is to be formed on one side or both sides of the sheet. In this case, if the information that the image is to be formed on single side of the sheet was obtained, the control means determines whether the image is to be formed or not on the sheet conveyed to the image forming means.
According to the present invention, for example, if the special sheet is held in the sheet holding tray with back side thereof up, the special sheet supplied from the sheet holding tray is conveyed to the image forming means with the back side of the sheet facing toward the image forming means.
For performing double-side printing, similar to the well-known image forming apparatus, when the front surface of the original was read, the control means stores the data of the read image (data corresponding to the image on the front surface of the original) in the image memory. Then, when the back surface of the original was read, the control means forms an image corresponding to the image on the back surface of the original on the special sheet (back side), reverses the special sheet and conveys it to the image forming means. Then, the control means forms an image corresponding to the image on the front surface of original on the special sheet (front side) using the stored data and discharges the special sheet to the sheet receiving tray. In this case, the special sheet is discharged to the receiving tray with the side, on which the image corresponding to the image on the front surface of the original is formed, facing down.
For performing single-side printing, when the front surface of the original was read, the control means stores data of the read image (data corresponding to the image on the front surface of the original) in the image memory and determines whether an image is to be formed or not on the special sheet (back side) conveyed to the image forming means. At this time, the control means determines not to form the image, performs idle conveyance, controls the reversal means to reverse the special sheet and conveys the special sheet to the image forming means. The control means then determines whether an image is to be formed or not on the special sheet (front side) conveyed to the image forming means. At this time, the control means determines to form the image, forms the image on the special sheet using the stored data and discharges the sheet to the sheet receiving tray. In this case, the special sheet is discharged to the sheet receiving tray with the image-formed side down.
Since the above-described image forming apparatus does not determine whether an image is to be formed or not on the sheet nor perform the idle conveyance when the double-side printing is performed, sheet conveyance time is reduced and efficiency at the time of image formation can be improved as compared with a case where conveyance and idle conveyance are performed to form an image on both sides of the sheet. In addition, since the conveyance distance of the sheet is reduced, a conveyance miss (jam, for example), deterioration of the sheet caused by the conveyance or the like can be prevented.
Although the image forming apparatus performs the conveyance and idle conveyance in order to form the image on the single side of the sheet for performing single-side printing, since the conveyance time and the conveyance distance are approximately the same as those of double-side printing, adverse effects on the sheet (a jam, deterioration of the sheet or the like) counts for nothing.
The image forming apparatus of the present invention may further comprise means for prohibiting determining whether an image is to be formed or not on the sheet conveyed to the image forming means when the obtained information is other than the information which requires determining whether the image is to be formed or not on the sheet conveyed to the image forming means.
For example, when the single-side printing is performed on the special sheet, since the special sheet has different attributes at respective sides, the image forming apparatus performs the conveyance and idle conveyance for forming the image on the single side of the sheet to form the image on the front side of the special sheet. Meanwhile, when the single-side printing is performed on the sheet other than the special sheet, since the sheet has the same attribute at both sides, only the conveyance for forming the image on the single side of the sheet is performed and it is not necessary to perform the idle conveyance.
In this case, the information that the sheet is the special sheet is the information (information corresponding to the sheet to be conveyed if it was determined that the image is to be formed and to be idly conveyed if it was determined that the image is not to be formed) to determine whether an image is to be formed or not on the sheet conveyed to the image forming means. In addition, the information that the sheet is other than the special sheet is other than the information which requires determining whether the image is to be formed or not on the sheet conveyed to the image forming means.
At this time, obtaining the information that the sheet is other than the special sheet, the image forming apparatus does not perform the idle conveyance by not determining whether the image is to be formed or not on the sheet conveyed to the image forming means. As a result, only the conveyance for forming the image on the single side of the sheet is performed.
Since the above image forming apparatus performs the image forming processing without performing the idle conveyance for the sheet which does not need the idle conveyance, the efficiency of the image formation is improved. Furthermore, deterioration of the sheet caused by the idle conveyance of the sheet, occurrence of a jam and the like can be prevented.
An image forming method according to the present invention is for forming an image on both sides of a sheet using the image forming apparatus of the present invention. The image forming method comprises a step of conveying a sheet to image forming means by conveying means with one side of the sheet facing toward the image forming means; a step of forming the image on the one side by the image forming means; a step of reversing the sheet by reversal means; a step of conveying the reversed sheet to the image forming means by the conveying means; a step of forming an image on the other side of the sheet by the image forming means; and a step of reversing the sheet by the reversal means.
According to the present invention, first of all, an original is read. In this case, it is determined that a front face of the original has been read. Then, a sheet is supplied by supply means and conveyed to image forming means by conveying means. Then, it is determined whether an image is to be formed or not on a sheet (one side) conveyed to the image forming means. At this time, it is determined to form the image and the image corresponding to the image on the front surface of the original is formed on the sheet.
Then, the original is read. In this case, it is determined that a back surface of the original has been read. Then, the sheet is reversed by reversal means and conveyed to the image forming means. Then, it is determined whether an image is to be formed or not on the sheet (the other side) conveyed to the image forming means. At this time, it is determined to form the image and the image corresponding to the image on the back surface of the original is formed on the sheet.
Last of all, the sheet is reversed by the reversal means and conveyed to the image forming means. Then, it is determined whether an image is to be formed or not on a sheet (the image-formed side) conveyed to the image forming means. At this time, it is determined not to form the image and the idle conveyance is performed to discharge the sheet to the sheet receiving tray.
In other words, double-side printing is performed and the idle conveyance is then performed.
As described above, sheets can be discharged to the sheet receiving tray in order of the originals with the side, on which the image corresponding to the image on the front surface of the original is formed, facing down.
In addition, since the sheet is idly conveyed after the image is formed on both sides of the sheet, image data for one surface of the original is stored in the image memory and the image is then formed. If image data for the other surface is stored, the image data is overwritten on the image data for the one surface and the image is then formed. Thus, it is not necessary to store the image data for both surfaces of the original in the image memory, whereby storage capacity of the image memory can be reduced.
An image forming method according to the present invention is for forming an image on both sides of a sheet using the image forming apparatus of the present invention. The image forming method comprises a step of conveying a sheet to image forming means by conveying means with one side of the sheet facing toward the image forming means; a step of reversing the sheet by reversal means; a step of conveying the reversed sheet to the image forming means by the conveying means; a step of forming an image on the other side of the sheet by the image forming means; a step of reversing the sheet by the reversal means; a step of conveying the reversed sheet to the image forming means by the conveying means; and a step of forming an image on the one side of the sheet by the image forming means.
According to the present invention, first of all, an original is read to generate first image data. In this case, it is determined that a front surface of the original has been read. Then, a sheet is supplied to supply means and conveyed to image forming means by conveying means. Then, it is determined whether an image is to be formed or not on a sheet (one side) conveyed to the image forming means. At this time, it is determined not to form the image and the idle conveyance is performed. In addition, the first image data is stored in an image memory.
Then, the original is read to generate second image data. In this case, it is determined that a back surface of the original has been read. Then, the sheet is reversed by reversal means and conveyed to the image forming means. Then, it is determined whether an image is to be formed or not on the sheet (the other side) conveyed to the image forming means. At this time, it is determined to form the image and the image to be generated using the second image data, i.e., the image corresponding to the image on the back surface of the original is formed on the sheet.
Last of all, the sheet is reversed by the reversal means and conveyed to the image forming means. Then, it is determined whether an image is to be formed or not on a sheet (one side) conveyed to the image forming means. At this time, it is determined to form the image and the image to be generated using the first image data stored in the image memory, i.e., the image corresponding to the image on the front surface of the original is formed on the sheet and the sheet is then discharged to the sheet receiving tray.
In other words, the idle conveyance is performed and double-side printing is then performed.
As described above, sheets can be discharged to the sheet receiving tray in order of the originals with the side, on which the image corresponding to the image on the front surface of the original is formed, facing down.
In addition, since the sheet on which image is not performed is idly conveyed and then, the image is formed on both sides of the sheet, even when a jam occurs during the idle conveyance, the image-formed sheet is not contaminated nor damaged. As a result, the image forming steps are not wasted.
An image forming method according to the present invention is for performing an image on one side of a sheet using the image forming apparatus of the present invention. The image forming method comprises a step of conveying a sheet to image forming means by conveying means with one side of the sheet facing toward the image forming means; a step of reversing the sheet by reversal means; a step of conveying the reversed sheet to the image forming means by the conveying means; and a step of forming an image on the other side of the sheet by the image forming means.
According to the present invention, first of all, an original is read to generate image data. Then, a sheet is supplied to supply means and conveyed to image forming means by conveying means. Then, it is determined whether an image is to be formed or not on a sheet (one side) conveyed to the image forming means. At this time, it is determined not to form the image and the idle conveyance is performed. In addition, the generated image data is stored in an image memory. Then, the sheet is reversed by the reversal means and conveyed to the image forming means. Then, it is determined whether an image is to be formed or not on a sheet conveyed to the image forming means. At this time, it is determined to form the image and the image generated using the stored image data is formed on the sheet (the other side) and the sheet is then discharged to the sheet receiving tray.
In other words, the idle conveyance is performed and single-side printing is then performed.
As described above, sheets can be discharged to the sheet receiving tray in order of the originals with the other side, on which the image is formed, facing down.
In addition, since the sheet on which no image is formed is idly conveyed and then, the image is formed on both sides of the sheet, even when a jam occurs during the idle conveyance, the image-formed sheet is not contaminated nor damaged. As a result, the image forming steps are not wasted.
An image forming method according to the present invention is for forming an image using the image forming apparatus of the present invention. According to the image forming method, if a plurality of sheets are sequentially processed, a plurality of pieces of information is sequentially obtained corresponding to the sheets and one of two pieces of information sequentially obtained is information for which it is to be determined whether an image is to be formed or not on a sheet conveyed to the image forming means and the other piece is information other than that information, the processing of the sheet corresponding to the other piece of information is started when the processing of the sheet corresponding to the one piece of information is completed.
According to the present invention, for performing the single-side printing on the special sheet, for example, since the special sheet has different attributes at respective sides, the special sheet is conveyed idly, reversed and then conveyed for forming the image on one side of the sheet in order to form the image on the front side of the special sheet. Meanwhile, for performing the single-side printing on the sheet other than the special sheet, since the sheet has the same attribute at both sides, only conveyance for forming the image on one side of the sheet is performed.
For sequentially performing the single-side printing for the special sheet after the single-side printing for the special sheet, even if the first special sheet in the subsequent single-side printing is fed when the last special sheet was reversed in the former single-side printing, the first special sheet in the subsequent single-side printing is also reversed and conveyed idly. As a result, the first special sheet is discharged to the sheet receiving tray after the last special sheet was discharged to the sheet receiving tray. In other words, each sheet is discharged to the sheet receiving tray in order of the originals.
However, for sequentially performing the single-side printing for the sheet other than the special sheet after the single-side printing for the special sheet, if the first sheet in the subsequent single-side printing is fed when the last special sheet in the former single-side printing is reversed and is not conveyed idly and not reversed, the fist sheet is sometimes discharged to the sheet receiving tray before the last special sheet is discharged to the sheet receiving tray. In addition, when the sheet is conveyed idly and reversed, although the first sheet is discharged after the last special sheet is discharged to the sheet receiving tray, since the idle conveyance is performed for the sheet which is not necessarily conveyed idly, a jam or deterioration of the sheet could occur and efficiency of image formation is decreased.
For performing the single-side printing for the sheet other than the special sheet when the single-side printing for the special sheet is completed (when the last special sheet is discharged to the sheet receiving tray or when the reversal and idle conveyance of the special sheet is completed, for example), the first sheet is prevented from being discharged to the sheet receiving tray before the last special sheet is discharged to the sheet receiving tray. In other words, each sheet can be discharged to the sheet receiving tray in order of the originals.
Thus, for sequentially processing a plurality of the sheets, if a plurality of pieces of information (information that the single-side printing is performed on the special sheet or information that the single-side printing is performed on the sheet other than the special sheet) is sequentially obtained corresponding to the sheets, one of two pieces of information sequentially obtained is information (in this case, the information that the single-side printing is performed on the special sheet) for which it is to be determined whether an image is to be formed or not on a sheet conveyed to the image forming means and the other piece of information is other than that information (the information that the single-side printing is performed for the sheet other than the special sheet), the processing (the single-side printing for the sheet other than the special sheet) of the sheet corresponding to the other piece of information is started when the processing (the single-side printing for the special sheet) of the sheet corresponding to the one piece of information is completed,. As a result, while the plurality of the sheets is sequentially processed, occurrence of a jam, deterioration of the sheet or decrease of efficiency of image formation is prevented and the sheets can be discharged in order of the originals.
The above and further objects and features of the present invention will more fully be apparent from the following detailed description with accompanying drawings.